1. Field of the Invention
This invention relates to an automatic system for sensing and preventing turnover of two-wheeled (single track) vehicles while enabling normal riding techniques in all but out of control situations.
2. Description of the Prior Art
Two wheeled, or single track, vehicles, such as bicycles, motorcycles and full body vehicles have long been commercially available. For safety reasons, manufacturers have added stabilizing means to the vehicles to stabilize it against overturning when stopped, moving at low speeds or when moving on wet or otherwise slippery roadways, the latter conditions causing tire slip to occur. The danger of overturning is increased when the vehicle is carrying a passenger because the passenger may make moves which could upset the driver or cause him to move incorrectly, so that together they destroy the normal lateral balance of the vehicle and thus overturn.
One prior art technique of stabilizing single track vehicles is to use a large passive gyro and utilize its precessional moment to control body roll. In U.S. Pat. No. 3,465,840 to Summers for example, the vehicle is stabilized against roll by a large brute force gyro having a lateral spin axis and a vertical gimbal axis. Roll equilibrium is maintained by application of a vehicle righting gimbal force as a function of gimbal precession rate. Gimbal drift resulting in gimbal displacement is erased by application of a drift correcting gimbal torque in the direction of the displacement.
While the method disclosed in Summers has met with some success in stabilizing large ships, the weight, expense and complexity of this method have barred two wheeled vehicles from using the method in an economical manner.
A second type of stabilizing method, which has been commercially available, uses retractable outrigger wheels. These wheels normally retract as the vehicle gains momentum and the driver assumes the responsibility of balancing the vehicle similar to a normal motorcycle. U.S. Pat. No. 3,700,059 to Sutton discloses a vehicle stabilizing system wherein the outrigger wheels can be steered in the direction of travel, rotated to meet road speed and raised or lowered through an electric, mechanized system.
The main drawback to all these outrigger wheel systems is that they do not provide automatic stability. All of these systems require the driver to decide when the outrigger wheels should be raised or lowered and then perform that function either manually or with a mechanized system.
A recent vehicle stabilization device using outrigger wheels is disclosed in U S. Pat. No. 4,513,837 to Archer. A control system is provided which includes a first operational mode in which the outrigger wheels are automatically retracted only at vehicle speeds above a pre-set level. A speed responsive switch is responsive to wind which enters an opening in the front housing grill. This automatic sensing technique for stabilization control purposes reacts only to vehicle speed and does not have means to control the vehicle from overturning above speeds of approximately 35 miles per hour.
A fourth method for vehicle stabilization is disclosed in U.S. Pat. No. 3,124,007 to Swinney and utilizes a moveable weight which is controlled by a gyro. The disadvantages of this system is that it is heavy, expensive and complex, the same disadvantages associated with the passive gyro systems set forth hereinabove.
In contrast, an automatic stabilization control system which is relatively inexpensive and lightweight, yet provides positive control to prevent overturning under any but the most severe circumstances would be a significant improvement to the aforementioned prior art systems.